Application of Pseudomonas fluorescens isolates to wheat as potential biological control agents against take‐all

Abstract

Two isolates of Pseudomonas fluorescens (2–79 and 13–79) from the USA were evaluated in the UK as biological control agents against Gaeumannomyces graminis var. tritici, the cause of take‐all in wheat. Biological control agents were applied as seed coatings in carboxymethyl cellulose (CMC) to seven wheat trials sown in 1987 and 1988 on fen peat and clay soils, and as peat‐based and microgranule formulations in one of these trials. In a trial of spring wheat on fen peat, all treatments with biological control agents reduced the percentage take‐all infection of crown roots and seminal roots, but the effects of only one isolate were statistically significant (P<0·05). Effects of biological control agents on infection rates in five other trials were not significant. In the trial in which application methods were compared, peat‐based inoculum initially appeared most effective but none of the treatments reduced take‐all significantly throughout the season. Application of biological control agents was associated with yield increases in several trials; these were not consistently associated with effects on take‐all. These results suggest that the isolates of P. fluorescens have potential to reduce take‐all and increase yields of wheat in the UK, but the beneficial effects are inconsistent. There is a need to develop isolates which reliably control severe take‐all in a variety of soil types.

Development of a powder formulation of Pseudomonas fluorescens for control of rice blast

“…Fluorescent pseudomonad strains have been reported to control diseases caused by soil-borne pathogens (Weller, 1988;Capper & Higgins, 1993;Vidhyasekaran & Muthamilan, 1995) and are known to survive in both rhizosphere and phyllosphere (Wilson et al, 1991;Beattie & Lindow, 1995). Earlier studies indicated that foliar diseases could be controlled by application of fluorescent pseudomonads as seed, soil or root treatments and it is presumed that they may induce systemic resistance and thus protect the leaves (Wei et al, 1991;Alstrom, 1991;Maurhofer et al, 1994).…”

“…Liu et al (1995) injected fluorescent pseudomonads into cotyledons for the control of a bacterial pathogen in cucumber. Injection or other methods of use of bacterial suspensions is impractical for large-scale application to control foliar diseases in the field (Capper & Higgins, 1993). A powder formulation with longer shelf life would be beneficial.…”

Crude extracts of Drimys winteri bark to inhibit growth of Gaeumannomyces graminis var. tritici

“…However, these methods are not satisfactory given their high cost and marginal effectiveness (Hornby, 1998;Apablaza, 1999;Cook, 2003). Various biological agents have been examined to control Ggt (Wong et al, 1996;Kim et al, 1997;Cook et al, 2002), though, none have been determined to be appropriate for a variety of soil conditions and production systems (Capper and Higgins, 1993;Cook, 2003).…”

Genetic Diversity and Biological Control Activity of Novel Species of Closely Related Pseudomonads Isolated from Wheat Field Soils in South Australia

“…The physical and chemical nature of soils varies greatly between agricultural regions; factors such as soil texture, organic matter, pH, water and oxygen availability, and competition for nutrients with indigenous microflora may significantly dampen the biological activity of introduced inocula. It has previously been demonstrated that an effective biological control strain isolated from one region may not perform in other soil and/or climatic conditions (5,10,16,31). For this reason, one of the important factors to be considered when screening new isolates is their activity in the range of environments in which they would be expected to be used, in particular different soil types.…”